The invention relates to a method and apparatus for detecting maxima and minima.
Various methods are known for detecting determining maxima (positive peaks) or minima (negative peaks) in a series of data points that generally form a sinusoidal wave.
U.S. Pat. No. 5,274,569 discloses a peak detector which identifies two sequential sets of two successive samples each. The first set includes samples on the leading edge and on either side of a threshold voltage Vt. The second set includes samples on the falling edge an on either side of the threshold voltage Vt. For each of the two sets, the point at which the signal substantially equals the threshold Vt is found by interpolation. The peak is determined as being equidistant between the two threshold points.
U.S. Pat. No. 5,319,583 discloses a sliding window minimum filter. A buffer is provided containing signal values currently within the sliding window. The local minimum and maximum points are determined within the buffer. This patent does not suggest comparing two marker points within a window to each other to determine the presence or absence of a maximum or minimum.
U.S. Pat. No. 4,183,087 discloses peak deviating sampling in which periodic sampling is performed by taking successive samples during an interval, determining interval maximal and minimal samples and determining the deviation of each maximal and minimal from the last sampling interval.